The present invention relates to a constant velocity universal ball joint having an outer joint part, with longitudinally extending internally circumferentially distributed first ball tracks, and an inner joint part with longitudinally extending externally circumferentially distributed second ball tracks. One first ball track and one second ball track each are arranged so as to be radially opposed. The outer joint part, at least at one end, includes an aperture for the drive means of the inner joint part. Torque transmitting balls are guided in each first and second ball track. An annular ball cage, which is positioned in an annular space between the outer joint part and the inner joint part, includes circumferentially distributed cage windows, each axially holding a ball. The ball cage holds all the balls in one common plane and when the axes of the outer joint part and of the inner joint part are articulated, guides the balls onto the angle-bisecting plane of same axes. The cage includes an outer spherical cage face, which is in guiding contact with a guiding face associated with the outer joint part, and an inner spherical cage face which is in guiding contact with a surface of the inner joint part.
Joints of this type are shown in DE-PS 22 52 827. As a rule, the outer joint part, at its driving end located axially opposite the drive end for the inner joint part, is closed by an integrally formed on base part. There are also prior art embodiments where such a base part is welded to the outer joint part. As a rule, a shaft journal is formed on or attached to the base part. The joints may be provided in the form of UF joints (undercut-free) with axially undercut-free ball tracks or as RF joints (Rzeppa fixed joints) whose ball tracks are curved on both sides of the central plane.
Joints of the above-mentioned type are complicated and disadvantageous as far as assembly is concerned. Initially, it is difficult to introduce the inner joint part into the cage with axes arranged perpendicularly relative to one another. It is equally complicated to introduce the cage into the outer joint part, again with the respective axes intersecting one another substantially at right angles, with parts of the cage engaging the tracks of the outer joint part and with parts of the outer joint part engaging the windows of the cage.
Only after the inner joint part, cage and outer joint part have been arranged inside one another, so as to be positioned substantially coaxially relative to one another, is it possible to fit the balls. Here the inner joint part, the cage and the outer joint part are moved into an individual angular position for each ball to enable the ball to be introduced radially into a cage window projecting from the outer joint part. To permit such an angular position referred to as "over-articulation" which, under normal joint operating conditions, is neither necessary nor permissible, the cage windows include a certain circumferential length which again is not required for standard operating conditions. As a result, the strength of the cage is reduced.